Hi,
here are some ideas. Since you did not give much context information about your application they might be more or less workable.
First I am wondering why the object you are trying to index does not define a association (OneToOne or whatever is appropriate) to this other object you want to load in the bridge? It could be a lazy loaded association there would really be no additional runtime cost. Why do you just store ids to some other objects and not real associations?
If you cannot use real associations you will need to get hold of the Session object or create a new one. I assume you have the whole Hibernate configuration wired up in Spring. As you say, you cannot configure your custom bridge in Spring. The best idea I have is to get hold of the Spring ApplicationContext within the bridge. Something like this could work
http://blog.jdevelop.eu/2008/07/06/acce ... plication/--Hardy